TreeSeg: Compute TreeCrown Segments

In SchoenbergA/CENITH: Segmentation tool

Description

computes polygon segments for TreeCrowns based on watershed algorithm

Usage

TreeSeg(
  chm = NULL,
  a,
  b,
  h,
  MIN = 0,
  MAX = 1000,
  CHMfilter = 1,
  silent = FALSE
)

Arguments

chm	raster - Canopy Height Model RasterLayer.
a	numeric - single value for MovingWindow.
b	numeric - single value for MovingWindow.
h	numeric - maximum height of trees (in meter) to detect trees.
MIN	numeric - the minimum area for crowns. Smaller polygons are cropped.
MAX	numeric - the maximum area for crowns. Larger polygons are cropped.
CHMfilter	numeric - uses a sum filter on the chm with a MovingWindow of (x*x), which must be odd. Default=1 no filter.
silent	bolean - if TRUE the function will not print any progress messages (default=FALSE).

Details

uses a MovingWindow of x*a+b to detect local maxima in a chm to compute TreeCrown Segments

• parameter selection - use BestSegVal to automated detect best fitting parameters for a, b, h, MIN and filter.

Value

returns a PolygonLayer with segments

Note

A 'brute force' segmentation with random parameters is not recommended. TreeSeg is mainly used to compute segments AFTER the validation of best fitting parameters with BestSegVal. Further to estimate the quality of the computed polygons it is recommended to use TreeSegCV for a x-fold CrossValdiation over x different subareas. For full workflow see the 'CENITH_Tutorial'.

Author(s)

Andreas Schönberg

See Also

BestSegVal,TreeSegCV

Examples

# load packages
require(CENITH)
require(raster)
require(mapview)
# load data
chm <- raster::raster(system.file("extdata","lau_chm.tif",package = "CENITH"))
# take a look on the data
plot(chm)
# NOTE: the example should NOT show to get optimal results (for this see 'BestSegVal')
# start segmentation
x <- TreeSeg(chm,a=0.3,b=0.5,h=1)
length(x)# amount of trees
# compare result with chm
mapview(chm)+x
# clip min and or max polygons
y <-TreeSeg(chm,a=0.2,b=0.5,h=2,MIN=10,MAX=100)
length(y)# amount of trees
mapview(chm)+y

SchoenbergA/CENITH documentation built on Sept. 7, 2021, 9:54 a.m.